Could treatment with immunomodulatory agents targeting IL-1, IL-6, or JAK signalling improve outcomes in patients with severe influenza pneumonia? A systematic and narrative review

Background: Influenza is a global cause of morbidity and mortality and a significant risk for a future pandemic infection. Host hyperinflammation, similar to that seen in COVID-19, may occur in response to influenza virus pneumonia, with Janus kinase (JAK) signalling and proinflammatory cytokines Interleukin (IL)-1 and IL-6 involved. Immune modulation treatment of hospitalised and critically ill COVID-19 patients, including with IL-6 and JAK inhibitors, has been found to be beneficial. Significant interest exists in the use of immunomodulatory agents targeting these pathways in the treatment of severe influenza pneumonia. Methods: We conducted a review with both systematic and narrative methods to assess whether, in patients with severe influenza pneumonia, treatment with immunomodulatory agents targeting IL-1, IL-6 or JAK signalling, in comparison to no immune modulation, is beneficial and improves clinical outcomes. Results: Our systematic search screened 5409 records and found no randomised controlled trials of IL-1, IL-6 or JAK immunomodulatory agents in patients with severe influenza pneumonia. To support this systematic search, we provide a narrative review of the biological rationale, previous use of these agents, including in hospitalised patients with COVID-19, and an overview of their safety profiles. Conclusions: Although immune modulation has proven successful in treating hospitalised and critically ill patients with COVID-19 and a biological rationale exists for testing these agents in influenza, no agents targeting IL-1, IL-6 or JAK signalling have been assessed in randomised controlled trials of patients with severe influenza pneumonia. This highlights a significant evidence gap.

The clinical and genomic epidemiology of seasonal human coronaviruses in congregate homeless shelter settings: A repeated cross-sectional study

Background

The circulation of respiratory viruses poses a significant health risk among those residing in congregate settings. Data are limited on seasonal human coronavirus (HCoV) infections in homeless shelter settings.

Methods

We analysed data from a clinical trial and SARS-CoV-2 surveillance study at 23 homeless shelter sites in King County, Washington between October 2019-May 2021. Eligible participants were shelter residents aged ≥3 months with acute respiratory illness. We collected enrolment data and nasal samples for respiratory virus testing using multiplex RT-PCR platform including HCoV. Beginning April 1, 2020, eligibility expanded to shelter residents and staff regardless of symptoms. HCoV species was determined by RT-PCR with species-specific primers, OpenArray assay or genomic sequencing for samples with an OpenArray relative cycle threshold <22.

Findings

Of the 14,464 samples from 3281 participants between October 2019-May 2021, 107 were positive for HCoV from 90 participants (median age 40 years, range: 0·9-81 years, 38% female). HCoV-HKU1 was the most common species identified before and after community-wide mitigation. No HCoV-positive samples were identified between May 2020-December 2020. Adults aged ≥50 years had the highest detection of HCoV (11%) among virus-positive samples among all age-groups. Species and sequence data showed diversity between and within HCoV species over the study period.

Interpretation

HCoV infections occurred in all congregate homeless shelter site age-groups with the greatest proportion among those aged ≥50 years. Species and sequencing data highlight the complexity of HCoV epidemiology within and between shelters sites.

Funding

Gates Ventures, Centers for Disease Control and Prevention, National Institute of Health.

Severe Acute Respiratory Infection-Preparedness: Protocol for a Multicenter Prospective Cohort Study of Viral Respiratory Infections

Respiratory virus infections cause significant morbidity and mortality ranging from mild uncomplicated acute respiratory illness to severe complications, such as acute respiratory distress syndrome, multiple organ failure, and death during epidemics and pandemics. We present a protocol to systematically study patients with severe acute respiratory infection (SARI), including severe acute respiratory syndrome coronavirus 2, due to respiratory viral pathogens to evaluate the natural history, prognostic biomarkers, and characteristics, including hospital stress, associated with clinical outcomes and severity.

DESIGN

Prospective cohort study.

SETTING

Multicenter cohort of patients admitted to an acute care ward or ICU from at least 15 hospitals representing diverse geographic regions across the United States.

PATIENTS

Patients with SARI caused by infection with respiratory viruses that can cause outbreaks, epidemics, and pandemics.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Measurements include patient demographics, signs, symptoms, and medications; microbiology, imaging, and associated tests; mechanical ventilation, hospital procedures, and other interventions; and clinical outcomes and hospital stress, with specimens collected on days 0, 3, and 7-14 after enrollment and at discharge. The primary outcome measure is the number of consecutive days alive and free of mechanical ventilation (VFD) in the first 30 days after hospital admission. Important secondary outcomes include organ failure-free days before acute kidney injury, shock, hepatic failure, disseminated intravascular coagulation, 28-day mortality, adaptive immunity, as well as immunologic and microbiologic outcomes.

CONCLUSIONS

SARI-Preparedness is a multicenter study under the collaboration of the Society of Critical Care Medicine Discovery, Resilience Intelligence Network, and National Emerging Special Pathogen Training and Education Center, which seeks to improve understanding of prognostic factors associated with worse outcomes and increased resource utilization. This can lead to interventions to mitigate the clinical impact of respiratory virus infections associated with SARI.

SARS-CoV-2 Screening Testing in Schools: A Comparison of School- Vs. Home-Based Collection Methods

We implemented a voluntary SARS-CoV-2 screening testing study for kindergarten-2nd grade students in a Washington School district. Weekly SARS-CoV-2 testing participation was higher for students with staff-collected nasal swabs at school than for students with parent-collected swabs at home.

Low quality antibody responses in critically ill patients hospitalized with pandemic influenza A(H1N1)pdm09 virus infection

Although some adults infected with influenza 2009 A(H1N1)pdm09 viruses mounted high hemagglutination inhibition (HAI) antibody response, they still suffered from severe disease, or even death. Here, we analyzed antibody profiles in patients (n = 31, 17-65 years) admitted to intensive care units (ICUs) with lung failure and invasive mechanical ventilation use due to infection with A(H1N1)pdm09 viruses during 2009-2011. We performed a comprehensive analysis of the quality and quantity of antibody responses using HAI, virus neutralization, biolayer interferometry, enzyme-linked-lectin and enzyme-linked immunosorbent assays. At time of the ICU admission, 45% (14/31) of the patients had HAI antibody titers ≥ 80 in the first serum (S1), most (13/14) exhibited narrowly-focused HAI and/or anti-HA-head binding antibodies targeting single epitopes in or around the receptor binding site. In contrast, 42% (13/31) of the patients with HAI titers ≤ 10 in S1 had non-neutralizing anti-HA-stem antibodies against A(H1N1)pdm09 viruses. Only 19% (6/31) of the patients showed HA-specific IgG1-dominant antibody responses. Three of 5 fatal patients possessed highly focused cross-type HAI antibodies targeting the (K130 + Q223)-epitopes with extremely low avidity. Our findings suggest that narrowly-focused low-quality antibody responses targeting specific HA-epitopes may have contributed to severe infection of the lower respiratory tract.

Influenza

Annual seasonal influenza epidemics of variable severity caused by influenza A and B virus infections result in substantial disease burden worldwide. Seasonal influenza virus circulation declined markedly in 2020-21 after SARS-CoV-2 emerged but increased in 2021-22. Most people with influenza have abrupt onset of respiratory symptoms and myalgia with or without fever and recover within 1 week, but some can experience severe or fatal complications. Prevention is primarily by annual influenza vaccination, with efforts underway to develop new vaccines with improved effectiveness. Sporadic zoonotic infections with novel influenza A viruses of avian or swine origin continue to pose pandemic threats. In this Seminar, we discuss updates of key influenza issues for clinicians, in particular epidemiology, virology, and pathogenesis, diagnostic testing including multiplex assays that detect influenza viruses and SARS-CoV-2, complications, antiviral treatment, influenza vaccines, infection prevention, and non-pharmaceutical interventions, and highlight gaps in clinical management and priorities for clinical research.

The Clinical and Genomic Epidemiology of Rhinovirus in Homeless Shelters-King County, Washington

BACKGROUND

Rhinovirus (RV) is a common cause of respiratory illness in all people, including those experiencing homelessness. RV epidemiology in homeless shelters is unknown.

METHODS

We analyzed data from a cross-sectional homeless shelter study in King County, Washington, October 2019-May 2021. Shelter residents or guardians aged ≥3 months reporting acute respiratory illness completed questionnaires and submitted nasal swabs. After 1 April 2020, enrollment expanded to residents and staff regardless of symptoms. Samples were tested by multiplex RT-PCR for respiratory viruses. A subset of RV-positive samples was sequenced.

RESULTS

There were 1066 RV-positive samples with RV present every month of the study period. RV was the most common virus before and during the coronavirus disease 2019 (COVID-19) pandemic (43% and 77% of virus-positive samples, respectively). Participants from family shelters had the highest prevalence of RV. Among 131 sequenced samples, 33 RV serotypes were identified with each serotype detected for ≤4 months.

CONCLUSIONS

RV infections persisted through community mitigation measures and were most prevalent in shelters housing families. Sequencing showed a diversity of circulating RV serotypes, each detected over short periods of time. Community-based surveillance in congregate settings is important to characterize respiratory viral infections during and after the COVID-19 pandemic.

CLINICAL TRIALS REGISTRATION

NCT04141917.

Clinical Outcomes of Monoclonal Antibody Therapy During a COVID-19 Outbreak in a Skilled Nursing Facility-Arizona, 2021

Background

Adult residents of skilled nursing facilities (SNF) have experienced high morbidity and mortality from SARS‐CoV‐2 infection and are at increased risk for severe COVID‐19 disease. Use of monoclonal antibody (mAb) treatment improves clinical outcomes among high‐risk outpatients with mild‐to‐moderate COVID‐19, but information on mAb effectiveness in SNF residents with COVID‐19 is limited. We assessed outcomes in SNF residents with mild‐to‐moderate COVID‐19 associated with an outbreak in Arizona during January–February 2021 that did and did not receive a mAb.

Methods

Medical records were reviewed to describe the effect of bamlanivimab therapy on COVID‐19 mortality. Secondary outcomes included referral to an acute care setting and escalation of medical therapies at the SNF (e.g., new oxygen requirements). Residents treated with bamlanivimab were compared to residents who were eligible for treatment under the FDA's Emergency Use Authorization (EUA) but were not treated. Multivariable logistic regression was used to determine association between outcomes and treatment status.

Results

Seventy‐five residents identified with COVID‐19 during this outbreak met eligibility for mAb treatment, of whom 56 received bamlanivimab. Treated and untreated groups were similar in age and comorbidities associated with increased risk of severe COVID‐19 disease. Treatment with bamlanivimab was associated with reduced 21‐day mortality (adjusted OR = 0.06; 95% CI: 0.01, 0.39) and lower odds of initiating oxygen therapy (adjusted OR = 0.07; 95% CI: 0.02, 0.34). Referrals to acute care were not significantly different between treated and untreated residents.

Conclusions

mAb therapy was successfully administered to SNF residents with COVID‐19 in a large outbreak setting. Treatment with bamlanivimab reduced 21‐day mortality and reduced initiation of oxygen therapy. As the COVID‐19 pandemic evolves and newer immunotherapies gain FDA authorization, more studies of the effectiveness of mAb therapies for treating emerging SARS‐CoV‐2 variants of concern in high‐risk congregate settings are needed.

Phylogenomics of SARS-CoV-2 in Emergency Shelters for People Experiencing Homelessness

Residents and staff of emergency shelters for people experiencing homelessness (PEH) are at high risk of infection with SARS-CoV-2. The importance of shelter-related transmission of SARS-CoV-2 in this population remains unclear. It is also unknown whether there is significant spread of shelter-related viruses into surrounding communities. We analyzed genome sequence data for 28 SARS-CoV-2-positive specimens collected from 8 shelters in King County, Washington between March and October, 2020. We identified at least 12 separate SARS-CoV-2 introduction events into these 8 shelters and estimated that 57% (16 out of 28) of the examined cases of SARS-CoV-2 infection were the result of intra-shelter transmission. However, we identified just a few SARS-CoV-2 specimens from Washington that were possible descendants of shelter viruses. Our data suggest that SARS-CoV-2 spread in shelters is common, but we did not observe evidence of wide-spread transmission of shelter-related viruses into the general population.

Trends in COVID-19 vaccination intent and factors associated with deliberation and reluctance among adult homeless shelter residents and staff, 1 November 2020 to 28 February 2021 - King County, Washington

Introduction

Little is known about COVID-19 vaccination intent among people experiencing homelessness. This study assesses surveyed COVID-19 vaccination intent among adult homeless shelter residents and staff and identifies factors associated with vaccine deliberation (responded “undecided”) and reluctance (responded “no”), including time trends.

Methods

From 11/1/2020–2/28/21, we conducted repeated cross-sectional surveys at nine shelters in King County, WA as part of ongoing community-based SARS-CoV-2 surveillance. We used a multinomial model to identify characteristics associated with vaccine deliberation and reluctance.

Results

A total of 969 unique staff (n = 297) and residents (n = 672) participated and provided 3966 survey responses. Among residents, 53.7% (n = 361) were vaccine accepting, 28.1% reluctant, 17.6% deliberative, and 0.6% already vaccinated, whereas among staff 56.2% were vaccine accepting, 14.1% were reluctant, 16.5% were deliberative, and 13.1% already vaccinated at their last survey. We observed higher odds of vaccine deliberation or reluctance among Black/African American individuals, those who did not receive a seasonal influenza vaccine, and those with lower educational attainment. There was no significant trend towards vaccine acceptance.

Conclusions

Strong disparities in vaccine intent based on race, education, and prior vaccine history were observed. Increased vaccine intent over the study period was not detected. An intersectional, person-centered approach to addressing health inequities by public health authorities planning vaccination campaigns in shelters is recommended.

Clinical Trial Registry Number: NCT04141917.

Interpretation of Relative Efficacy and Effectiveness for Influenza Vaccines

Relative vaccine effectiveness (rVE) are metrics commonly reported to compare absolute VE (aVE) of two vaccine products. Estimates of rVE for enhanced influenza vaccines (eIV) vs. standard inactivated influenza vaccine (IIV) have been assessed across different seasons, influenza-specific endpoints, and nonspecific endpoints (e.g., all-cause cardiovascular hospitalizations). To illustrate the challenges of comparability across studies, we conducted a scenario analysis to evaluate the effects of varying absolute VE (aVE) of IIV (i.e., as compared with placebo) on the interpretation of rVE of eIV vs IIV. We show that estimates of rVE might not be comparable across studies because additional benefits commensurate with a given estimate of rVE are dependent on the aVE for the comparator vaccine, which can depend on factors such as host response to vaccine, virus type, and clinical endpoint evaluated. These findings have implications for interpretation of rVE across studies and for sample size considerations in future trials.

Remote Household Observation for Noninfluenza Respiratory Viral Illness

BACKGROUND

Noninfluenza respiratory viruses are responsible for a substantial burden of disease in the United States. Household transmission is thought to contribute significantly to subsequent transmission through the broader community. In the context of the coronavirus disease 2019 (COVID-19) pandemic, contactless surveillance methods are of particular importance.

METHODS

From November 2019 to April 2020, 303 households in the Seattle area were remotely monitored in a prospective longitudinal study for symptoms of respiratory viral illness. Enrolled participants reported weekly symptoms and submitted respiratory samples by mail in the event of an acute respiratory illness (ARI). Specimens were tested for 14 viruses, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), using reverse-transcription polymerase chain reaction. Participants completed all study procedures at home without physical contact with research staff.

RESULTS

In total, 1171 unique participants in 303 households were monitored for ARI. Of participating households, 128 (42%) included a child aged <5 years and 202 (67%) included a child aged 5-12 years. Of the 678 swabs collected during the surveillance period, 237 (35%) tested positive for 1 or more noninfluenza respiratory viruses. Rhinovirus, common human coronaviruses, and respiratory syncytial virus were the most common. Four cases of SARS-CoV-2 were detected in 3 households.

CONCLUSIONS

This study highlights the circulation of respiratory viruses within households during the winter months during the emergence of the SARS-CoV-2 pandemic. Contactless methods of recruitment, enrollment, and sample collection were utilized throughout this study and demonstrate the feasibility of home-based, remote monitoring for respiratory infections.

Sampling for SARS-CoV-2 Aerosols in Hospital Patient Rooms

Evidence varies as to how far aerosols spread from individuals infected with SARS-CoV-2 in hospital rooms. We investigated the presence of aerosols containing SARS-CoV-2 inside of dedicated COVID-19 patient rooms. Three National Institute for Occupational Safety and Health BC 251 two-stage cyclone samplers were set up in each patient room for a six-hour sampling period. Samplers were place on tripods, which each held two samplers at various heights above the floor. Extracted samples underwent reverse transcription polymerase chain reaction for selected gene regions of the SARS-CoV-2 virus nucleocapsid. Patient medical data were compared between participants in rooms where virus-containing aerosols were detected and those where they were not. Of 576 aerosols samples collected from 19 different rooms across 32 participants, 3% (19) were positive for SARS-CoV-2, the majority from near the head and foot of the bed. Seven of the positive samples were collected inside a single patient room. No significant differences in participant clinical characteristics were found between patients in rooms with positive and negative aerosol samples. SARS-CoV-2 viral aerosols were detected from the patient rooms of nine participants (28%). These findings provide reassurance that personal protective equipment that was recommended for this virus is appropriate given its spread in hospital rooms.

Influenza

Seasonal influenza epidemics of variable severity pose challenges to public health. Annual vaccination is the primary way to prevent influenza, and a wide range of vaccines are available, including inactivated or live attenuated standard-dose, recombinant vaccines, as well as adjuvanted or high-dose vaccines for persons aged 65 years or older. Persons at increased risk for influenza complications include young children, persons with underlying medical conditions, and older adults. Prompt diagnosis of influenza can facilitate early initiation of antiviral treatment that provides the greatest clinical benefit. This article summarizes recommendations for providers on influenza vaccination, diagnostic testing, and antiviral treatment.

Microbial signatures in the lower airways of mechanically ventilated COVID-19 patients associated with poor clinical outcome

Respiratory failure is associated with increased mortality in COVID-19 patients. There are no validated lower airway biomarkers to predict clinical outcome. We investigated whether bacterial respiratory infections were associated with poor clinical outcome of COVID-19 in a prospective, observational cohort of 589 critically ill adults, all of whom required mechanical ventilation. For a subset of 142 patients who underwent bronchoscopy, we quantified SARS-CoV-2 viral load, analysed the lower respiratory tract microbiome using metagenomics and metatranscriptomics and profiled the host immune response. Acquisition of a hospital-acquired respiratory pathogen was not associated with fatal outcome. Poor clinical outcome was associated with lower airway enrichment with an oral commensal (Mycoplasma salivarium). Increased SARS-CoV-2 abundance, low anti-SARS-CoV-2 antibody response and a distinct host transcriptome profile of the lower airways were most predictive of mortality. Our data provide evidence that secondary respiratory infections do not drive mortality in COVID-19 and clinical management strategies should prioritize reducing viral replication and maximizing host responses to SARS-CoV-2.

Comparison of Symptoms and RNA Levels in Children and Adults With SARS-CoV-2 Infection in the Community Setting

Importance

The association between COVID-19 symptoms and SARS-CoV-2 viral levels in children living in the community is not well understood.

Objective

To characterize symptoms of pediatric COVID-19 in the community and analyze the association between symptoms and SARS-CoV-2 RNA levels, as approximated by cycle threshold (Ct) values, in children and adults.

Design, Setting, and Participants

This cross-sectional study used a respiratory virus surveillance platform in persons of all ages to detect community COVID-19 cases from March 23 to November 9, 2020. A population-based convenience sample of children younger than 18 years and adults in King County, Washington, who enrolled online for home self-collection of upper respiratory samples for SARS-CoV-2 testing were included.

Exposures

Detection of SARS-CoV-2 RNA by reverse transcription-polymerase chain reaction (RT-PCR) from participant-collected samples.

Main Outcomes and Measures

RT-PCR-confirmed SARS-CoV-2 infection, with Ct values stratified by age and symptoms.

Results

Among 555 SARS-CoV-2-positive participants (mean [SD] age, 33.7 [20.1] years; 320 were female [57.7%]), 47 of 123 children (38.2%) were asymptomatic compared with 31 of 432 adults (7.2%). When symptomatic, fewer symptoms were reported in children compared with adults (mean [SD], 1.6 [2.0] vs 4.5 [3.1]). Symptomatic individuals had lower Ct values (which corresponded to higher viral RNA levels) than asymptomatic individuals (adjusted estimate for children, -3.0; 95% CI, -5.5 to -0.6; P = .02; adjusted estimate for adults, -2.9; 95% CI, -5.2 to -0.6; P = .01). The difference in mean Ct values was neither statistically significant between symptomatic children and symptomatic adults (adjusted estimate, -0.7; 95% CI, -2.2 to 0.9; P = .41) nor between asymptomatic children and asymptomatic adults (adjusted estimate, -0.6; 95% CI, -4.0 to 2.8; P = .74).

Conclusions and Relevance

In this community-based cross-sectional study, SARS-CoV-2 RNA levels, as determined by Ct values, were significantly higher in symptomatic individuals than in asymptomatic individuals and no significant age-related differences were found. Further research is needed to understand the role of SARS-CoV-2 RNA levels and viral transmission.

Developing Treatment Guidelines During a Pandemic Health Crisis: Lessons Learned From COVID-19

The development of the National Institutes of Health (NIH) COVID-19 Treatment Guidelines began in March 2020 in response to a request from the White House Coronavirus Task Force. Within 4 days of the request, the NIH COVID-19 Treatment Guidelines Panel was established and the first meeting took place (virtually-as did subsequent meetings). The Panel comprises 57 individuals representing 6 governmental agencies, 11 professional societies, and 33 medical centers, plus 2 community members, who have worked together to create and frequently update the guidelines on the basis of evidence from the most recent clinical studies available. The initial version of the guidelines was completed within 2 weeks and posted online on 21 April 2020. Initially, sparse evidence was available to guide COVID-19 treatment recommendations. However, treatment data rapidly accrued based on results from clinical studies that used various study designs and evaluated different therapeutic agents and approaches. Data have continued to evolve at a rapid pace, leading to 24 revisions and updates of the guidelines in the first year. This process has provided important lessons for responding to an unprecedented public health emergency: Providers and stakeholders are eager to access credible, current treatment guidelines; governmental agencies, professional societies, and health care leaders can work together effectively and expeditiously; panelists from various disciplines, including biostatistics, are important for quickly developing well-informed recommendations; well-powered randomized clinical trials continue to provide the most compelling evidence to guide treatment recommendations; treatment recommendations need to be developed in a confidential setting free from external pressures; development of a user-friendly, web-based format for communicating with health care providers requires substantial administrative support; and frequent updates are necessary as clinical evidence rapidly emerges.

A remote household-based approach to influenza self-testing and antiviral treatment

Background

Households represent important settings for transmission of influenza and other respiratory viruses. Current influenza diagnosis and treatment relies upon patient visits to healthcare facilities, which may lead to under‐diagnosis and treatment delays. This study aimed to assess the feasibility of an at‐home approach to influenza diagnosis and treatment via home testing, telehealth care, and rapid antiviral home delivery.

Methods

We conducted a pilot interventional study of remote influenza diagnosis and treatment in Seattle‐area households with children during the 2019‐2020 influenza season using pre‐positioned nasal swabs and home influenza tests. Home monitoring for respiratory symptoms occurred weekly; if symptoms were reported within 48 hours of onset, participants collected mid‐nasal swabs and used a rapid home‐based influenza immunoassay. An additional home‐collected swab was returned to a laboratory for confirmatory influenza RT‐PCR testing. Baloxavir antiviral treatment was prescribed and delivered to symptomatic and age‐eligible participants, following a telehealth encounter.

Results

124 households comprising 481 individuals self‐monitored for respiratory symptoms, with 58 home tests administered. 12 home tests were positive for influenza, of which eight were true positives confirmed by RT‐PCR. The sensitivity and specificity of the home influenza test were 72.7% and 96.2%, respectively. There were eight home deliveries of baloxavir, with 7 (87.5%) occurring within 3 hours of prescription and all within 48 hours of symptom onset.

Conclusions

We demonstrate the feasibility of self‐testing combined with rapid home delivery of influenza antiviral treatment. This approach may be an important control strategy for influenza epidemics and pandemics.

Clinical Effectiveness and Safety of Antivirals for Influenza in Pregnancy

Seasonal influenza epidemics result in substantial health care burden annually. Early initiation of antiviral treatment of influenza has been shown to reduce the risk of complications and duration of illness. Pregnant and postpartum women may be at increased risk for influenza-associated complications; however, pregnant women have been generally excluded from clinical trials of antiviral treatment of influenza. In this review, we summarize the available evidence on the clinical effectiveness and safety of antiviral treatment of pregnant women with influenza. Observational data show a reduction of severe outcomes when pregnant and postpartum women are treated with oseltamivir and other neuraminidase inhibitors without increased risk of adverse maternal, fetal, or neonatal outcomes. Due to lack of safety and efficacy data for baloxavir treatment of pregnant and postpartum women, baloxavir is currently not recommended for use in these populations.

Evidence of Severe Acute Respiratory Syndrome Coronavirus 2 Replication and Tropism in the Lungs, Airways, and Vascular Endothelium of Patients With Fatal Coronavirus Disease 2019: An Autopsy Case Series

Background

The coronavirus disease 2019 (COVID-19) pandemic continues to produce substantial morbidity and mortality. To understand the reasons for the wide-spectrum complications and severe outcomes of COVID-19, we aimed to identify cellular targets of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) tropism and replication in various tissues.

Methods

We evaluated RNA extracted from formalin-fixed, paraffin-embedded autopsy tissues from 64 case patients (age range, 1 month to 84 years; 21 COVID-19 confirmed, 43 suspected COVID-19) by SARS-CoV-2 reverse-transcription polymerase chain reaction (RT-PCR). For cellular localization of SARS-CoV-2 RNA and viral characterization, we performed in situ hybridization (ISH), subgenomic RNA RT-PCR, and whole-genome sequencing.

Results

SARS-CoV-2 was identified by RT-PCR in 32 case patients (21 COVID-19 confirmed, 11 suspected). ISH was positive in 20 and subgenomic RNA RT-PCR was positive in 17 of 32 RT-PCR–positive case patients. SARS-CoV-2 RNA was localized by ISH in hyaline membranes, pneumocytes, and macrophages of lungs; epithelial cells of airways; and endothelial cells and vessel walls of brain stem, leptomeninges, lung, heart, liver, kidney, and pancreas. The D614G variant was detected in 9 RT-PCR–positive case patients.

Conclusions

We identified cellular targets of SARS-CoV-2 tropism and replication in the lungs and airways and demonstrated its direct infection in vascular endothelium. This work provides important insights into COVID-19 pathogenesis and mechanisms of severe outcomes.